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M.31-33
The M.31 '''and the M.33 were the standard military gas masks of the REI (Regio Esercito Italiano, royal Italian army) from 1931 until 1949. A variant modified in Spain of both of these two masks was made, and it was issued to Nationalist belligerents during the Spanish Civil War and shortly after. History '''Development During the late '20s, the Italian Army was seeking renovation in its chemical protection equipment. Since the end of the war, in fact, the Army was still using Small Box Respirators, which were considered outdated by every standard after the second half of the '20s. Because of that push, the army adopted the Penna Respirator in 1928. Although superior to the SBR, the design had some issues which brought the army to seek a new respirator, a search that ended in 1931 with the adoption of the M.31. Improvements This new design had the following improvements: * Stiffer rubber and a different shape of the faceblank, especially around the connection with the metal assembly at the front, reduced drastically the instability of the latter, avoiding it from restricting airflow. * The filter was completely overhauled, as the SBR-like shape was dropped in favour of a round one. The content was changed, making breathing easier, and the plug was now attached with a string, preventing it from being lost as easily. * The 6-straps system was changed to a 5-straps one, as the latter had all of the elastic straps replaceable. * The metal assembly was changed in such a way to allow easier maintenance of the inlet and exhale valves, the latter of which also saw a change in design, as the aluminium base was made of rubber instead, and because of that, there was no need for a gasket in between it and the assembly. Both valves were interchangeable between the two designs. * The eyepieces were now crimped and could be replaced with little to no equipment Adoption and first uses Spanish civil war use During the Spanish Civil War, the M.31-33 was issued both in the regular configuration and a specially crafted one made by Draeger-Blanco with a German intake assembly and a different kit. Second World War 16002931 1300527923319070 1753814886861740606 n.jpg|Abandoned Italian gas masks (including M.31-33s) after the second El Alamein battle, 1942 Post-war use Regular Italian variant |countries-issued = |weight = Full kit : 2050 ± 50 g (depending on the size of the mask)|thread = ------------------------------------------------------------------------------------------ only for modified variants, |manufacturer = I.A.C. Pirelli|issued = |period = 1931-1949}} Mask overview The M.31 and M.33 facepieces are completely identical, saving the markings. The mask is composed of the following parts: The faceblank, made of moulded rubber, has the following parts attached to it: * the housing for the exhale and intake valves * the internal half-mask * the hose * the eyepieces * the straps At the bottom-front of the mask, there is a milled metal assembly with a mount for an intake valve, one for the exhale valve and its threaded lid, and two holes to connect said piece to the faceblank and the hose. The intake valve is a simple rubber disc placed over the hole where the hose is attached. The exhale valve is made of rubber, and it can be easily inspected and possibly replaced by unscrewing the lid of its housing. Attached to the same end of the metal assembly as the faceblank there is an internal half-mask, made of black rubber. Its role is to reduce the dead space in the mask to a bare minimum by almost completely preventing airflow outside the mouth and nose area. To the outmost end of the metal assembly, the rubber hose is attached. It's corrugated and connects the mask to the filter. The eyepieces are made of "Triplex" glass, which itself is composed of two glass layers and a thin sheet of cellulose. This kind of glass prevents poisoned air to get into the mask even after being hit, as only the outside layer of glass would be shattered and the other two layers would maintain the seal. The glasses are affixed to the mask through aluminium frames. The elastic harness has the goal to keep the mask tightly onto the face. It is composed of 5 adjustable straps (a top one, two elastic temple ones and two elastic cheek ones) attached to the facepiece, and they gather into a nape pad. The anti-fogging disks are kept tightly onto the lenses by metal inserts and serve the purpose of maintaining good visibility. The mask was marked on the inside of the facepiece with a register number, on the internal half-mask with the size and producer's logo, on the external right side with the kit's register number, on the hose with the year of production and the producer's logo, on the exhale valve with the producer's logo and on the external left side of the facepiece with the size, the producer's logo, the name of the mask and a series of dots that indicated the year of production, following the logic of mask name's year (either 1931 or 1933 in this case) + the number of dots (which could also not be there, meaning the mask was made in that exact year). IMG_20191223_165827.jpg|Front IMG 20191223 165849.jpg|Left side IMG_20191223_165921.jpg|Right side IMG_20191223_170109.jpg|Metal assembly disassembled IMG_20191223_170548.jpg|Strap system IMG_20191223_170951.jpg|Inside IMG_20191223_170835.jpg|Marking on the right side IMG_20191223_204650.jpg|Marking on the left side IMG_20191223_204632.jpg|Marking on the internal half-mask IMG_20191223_170002.jpg|Marking on the hose IMG_20191223_171127.jpg|Marking on the inside, under the right eye Filter The filter was the only main difference between the M.31 and M.33 masks and the only reason why M.33 masks, even though identical to M.31s, had their designation changed. M.31 and M.33 filters differed in content, but not in shape, and therefore both fit the following description: The body is a cylinder made of aluminium painted dark brown. The diameter is 11 cm, the height is 21 cm and the weight is around 1 kg. On the upper side, there's a collar that is connected to the hose. On the bottom, there's a hole that lets the poisoned air in and, while the mask is not in use, it can be closed using a rubber plug attached through a string to the filter. This plug system was an upgrade over the Penna filter as the plug couldn't be lost as easily, so much so that it will be used in some form or another until the adoption of the M90. Inside the filter, there were riddled metal sheets that divided the filtrating layers, with the down most one having a spring that pushed the metal sheet upwards to create a small air chamber and making breathing easier. The filter was marked on the side and on the bottom with 4 letters, the first letter indicating the year of manufacture ("A" is for 1931, "B" is for 1932 and so on), and the other 3 indicating the filtrating layers in order from the top to the bottom of the filter. The filter also had a few lines of instructions at the top with the producer's logo and an additional date marking at the bottom (the latter with some exceptions, for unknown reasons). Unissued filters were plugged at the bottom with waxed canvas and at the top with a cork, and they were protected with some cardboard around the main body. M.31-33 filters markings' key Note that this key does not refer to the first letter of the marking, that indicates the year of production. * c = massa antifumo, smokeproof mass * z = granuli, granules * a = carbone attivo di torba, peat activated charcoal * g = carbone attivo G.1000, G.1000 activated charcoal M.31 M.31 filters are marked with either an "A", a "B" (or in very rare cases a "C") as their starting letter and then "c", "a" and "z". Due to the adoption of the M.33 filter, M.31 filters ceased being produced in 1932. Some filters can be marked as "M33" followed by a date; this means the filter was re-issued. M.31 filters were in fact not much worse in comparison to M.33 filters, and they kept being used alongside them until they couldn't be used anymore. The autonomy was similar to M.33 filters, possibly just a little bit shorter, but currently, there is no data available on this topic. The waxed canvas plug is circular. sdfdhyfhjfghfghf.jpg|Marking from a plugged M.31 filter fgdfhfgjghjfghfgh.jpg|Re-issued M.31 filter with "M33" marking 67710384_10217450860957968_2581973590614212608_o.jpg|Rare C.c.a.z. M.31 filter attached to a Penna respirator Transitional M.31 In early 1933 some M.31 filters were produced with the "g" layer instead of the "a" layer as in previous instances. This filter saw very limited production and its full designation is always: "C.c.g.z.". The waxed canvas plug is circular. uwusdfsdfsd.jpg nouzsadsd.jpg M.33 M.33 filters were marked with a "C" or a letter after this one as the starting letter and then "z", "g" and "c". These filters had an extra air chamber inside the filter between the "c" and the "g" layer to further ease breathing. The autonomy of M.33 filters was around 15 hours with all gasses even with a high concentration with the exception of arsines, which reduced the autonomy to a degree, and CO, which was not filtered at all. The waxed canvas plug is square. 23er2vergfsergsrdh.jpg|M.33 filter from 1933 sdgdhdfghfdgf.jpg|M.33 filter from 1934 IMG_20191223_162220.jpg|Bottom marking IMG_20191223_162150.jpg|Top of the filter Kit Standard variant Regular M.31 and M.33 masks were issued with a kit similar to the one previously seen with the Penna respirator, but there were major changes and improvements. The kit comprises of: * M.31 carrier * M.31 or M.33 filter * An envelope with spare anti-fogging lenses * A small box with a spare exhale valve The carrier was a square bag divided into two parts, one for storing the mask while not in use and the other to keep the filter. In the latter, an angled piece of metal kept the intake hole of the filter elevated from the bottom of the carrier to allow free airflow. On the front of the carrier, there are two small pockets that are used to store the extra anti-fogging lenses and the spare exhale valve. The carrier is closed with two tabs at the front and automatic button between the two cloth parts over the inside. The strap system comprises a quickly-reduceable shoulder strap and a twine string. When the kit was carried, the soldier would keep the shoulder strap extended and adjusted based on their height, while in case of gas alert the shoulder strap would be shortened using a special tab, the carrier would be placed on the chest and the twine string, through two metal loops in the carrier, would be used to fasten the carrier tightly onto the wearer's chest to avoid it from bouncing. The bag's quality varied during the years, with later models having less fine knitting and a tab like the ones on the front on the part where the automatic button would be. The filter was kept on the left part of the bag. M.31 kits were issued with both M.31 and M.33 filters, while M.33 kits were issued only with M.33 filters. The M.31 and M.33 were usually issued with two pairs of anti-fogging lenses, one pair was already installed on the mask while the other was still in its envelope and inside one of the two front pockets. Unissued kits don't have anti-fogging lenses already installed. The envelope was marked in various ways depending on the production date, with the difference being the name of the mask written on it, which were "M.31, M.31-33, M.31-33 e (and in Italian) T.35", but the content did not change the slightest. The spare exhale valve was stored in a small box kept in one of the two front pockets. The design of the box varies depending on the producer and the model, with M.31 ones being slightly smaller, but the content was the same. IMG_20191223_161946.jpg|Unissued M.33 kit IMG_20191223_162106.jpg|Same kit without the cardboard around the filter IMG_20191223_162114.jpg|Spare exhale valve box. Note the marking IMG_20191223_162129.jpg|Anti-fogging lenses IMG_20191223_163108.jpg|Two M.31 bags, an early one on the left and a late one on the right IMG_20191223_163134.jpg|Same bags, from above. Note the automatic button on the left and the tab on the right IMG_20191223_163213.jpg|Same bags, detail of each strap. Note the lower quality of the later model (right) IMG_20191223_171728.jpg|Marking on the bag Threaded variant The replacement of M.31 and M.33 filters was very laborious, as tape and wire were needed for each substitution, making this process unpractical on the field. This operation was much easier and quicker with threaded intakes, which, in case of a chemical attack, would be determining. To solve this problem, some M.31 and M.33 masks were fitted with a threaded intake at the end of the hose which would allow T.35 filters and other threaded filters to be attached. This way the "maschera antigas M.33 modificata" (modified M.33 gas mask) was born. The kit was almost the same as the regular variant, differing only in the filters issued, which were 2 T.35 ones for each kit. This was done because T.35 filters lasted only half as much as M.33 ones, and therefore a spare filter was issued to maintain the long autonomy of the regular M.31-33 kit. IMG_20191223_162848.jpg|Modified M.33 kit. Note the threaded piece at the end of the hose Spanish variant ... |country = |manufacturer = Draeger-Blanco (assembled) Pirelli or I.A.C. (facepiece) Draeger (connector piece)|filter = Dräger-Blanco CMP|issued = }}The regular M.31-33 facepiece was deprived of its oral-nasal cup and its intake-outtake piece, which were substituted with a German GM-30 intake-outtake assembly, making the mask able to accept German 40 mm threaded filters. The mask was issued with a Spanish filter (as seen in the infobox) and either a Spanish bag or a German container. Some times the mask was kit implemented also Italian anti-fogging lenses, depending on the presence or not of metal clamps to support the aforementioned. Modified M.31 by IAC asfdfghfgafdsedf.JPG|Full kit. Note the Spanish bag generale.JPG|Mask with filter interno.JPG|Inside marchio lato sinistro.JPG|Marking Modified M.31 by Pirelli S-l1600-2.jpg|Full kit. Note the anti-fogging lenses S-l16s00.jpg|Marking S-lasd1600.jpg|Mask with filter Rebreathers ... Videos * A very thorough description of use and care for the M.31-33 Category:Italy Category:Military Gas Masks Category:Full Face Masks Category:World War II Era Mask Category:Rebreather Category:Spain Category:Interwar Era Mask